Facile Electrodeposition of Ti5Si3 Films from Oxide Precursors in Molten CaCl2

Abstract

It is hard to produce dense refractory Ti5Si3 films at low temperature because of the extremely high melting point (2130 °C) of Ti5Si3. Herein, we report the facile electrodeposition of Ti5Si3 films from TiO2 and SiO2 in molten CaCl2-CaO at 850 °C. Crystalline Ti5Si3 films with tunable film thicknesses and morphologies can be obtained in a controlled manner. The dissolution-electrodeposition processes were systematically investigated by cyclic voltammetry (CV), in-situ X-ray diffraction (XRD), in-situ Raman analysis, etc., and the synthesized Ti5Si3 products were characterized by electron backscattered diffraction (EBSD), transmission electron microscopy (TEM), three-dimensional atomic probe (3DAP), etc. The results show that the morphology of the products can be significantly influenced by current density. By controlling current density at the range from 10 to 25 mA cm−2, Ti5Si3 products with different morphologies, i.e., dendritic particles, dense films, and porous powders, can be obtained in a controlled manner. Besides, Ti, Si atoms uniformly distributed in the films. The reaction mechanism of the formation of Ti5Si3 film was also proposed, which can be summarized as three periods: CaO-assisted dissolution of SiO2 and TiO2, the electrodeposition of Si and Ti, and the formation of stable Ti5Si3 phase. The CaO-assisted dissolution-electrodeposition process may provide a promising strategy for the production of Ti5Si3 alloy films and powders.